共查询到18条相似文献,搜索用时 140 毫秒
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大麦中的酚类化合物及相关酶(如酚类合成酶苯丙氨酸解氨酶,酚类氧化酶过氧化物酶和多酚氧化酶)对大麦的生长发育、抗病特性及啤酒质量有重要影响。本文研究了16种不同品种、22种不同样本啤酒大麦中酚类物质的含量及相关酶活性的差异性和相关性,并测定了不同品种大麦的抗氧化活力。研究结果表明:不同品种和同一品种不同产地啤酒大麦的酚类化合物含量和酚类酶活性因品种特性和生长、种植条件而存在显著差异(P<0.05);游离总多酚含量和抗氧化力之间存在显著的正相关性(r=0.794);苯丙氨酸解氨酶活性并不与游离总多酚含量呈正相关性,过氧化物酶和多酚氧化酶的活性也不与总多酚含量呈相关性,这可能和大麦中同时存在酶类氧化酶和酚类合成酶有关。研究认为,通过测定大麦游离总多酚含量和DPPH自由基清除率可初步判断啤酒大麦的内源性抗氧化力,以此作为评价酿造原料品质的检测手段。 相似文献
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大麦、麦芽和啤酒酿造中的内源性氧化还原酶 总被引:1,自引:1,他引:1
由于大麦和麦芽中存在的内潭性氧化还原酶的作用,使内源性多酚、不饱和脂类等物质被氧化,导致成品啤酒风味稳定性和非生物稳定性的降低。酶促氧化反应可发生在不同的酿造阶段,包括发芽、焙爆和糖化等环节。五种主要的内源性氧化还原酶中,超氧化物歧化酶是最为重要的抗氧化酶,可防止超氧阴离子自由基的危害;而过氧化氢酶可催化具有活性的H2O2生成如,由此构成了清除活性氧的初级抗氧化酶体系。过氧化物酶和多酚氧化酶分别在H2O2和O2存在的情况下,可催化内源性酚类底物生成具有活性的醌类物质,所产生的次级氧化产物可改变啤酒的品质。脂肪酸氧化酶可氧化不饱和脂肪酸生成可挥发性的醛类物质,是导致啤酒风味老化的关键酶。酶促氧化的结果在成品啤酒上主要表现为老化异昧的出现、形成混浊、苦味和收敛性的改变,以及色泽的加深等。本文综述了这五种酶的基本性质,在制麦和糖化过程中的变化及其影响,并探讨了对啤酒酿造的影响。 相似文献
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研究了3种典型国产啤酒大麦在麦芽制造过程中(包括浸麦、发芽和干燥)酚类物质及其相关酶类(苯丙氨酸解氨酶:phenylalanine ammonia-lyase,PAL、过氧化物酶:peroxidase,POD和多酚氧化酶:polyphenol oxidase,PPO)的变化,分析了制麦过程中酚类物质含量的变化与酶活力和制麦工艺之间的关系,讨论了大麦发芽过程中苯丙氨酸解氨酶在合成酚类物质方面的作用及过氧化物酶对根芽生长和制麦损失的影响。 相似文献
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果蔬采后酶促褐变机理及影响褐变的因素研究进展 总被引:1,自引:0,他引:1
综述了果蔬采后酶促褐变过程中与褐变有关的酶如多酚氧化酶、过氧化物酶等的反应机理,反应底物酚类物质的反应机理及分类,以及影响褐变的因素研究进展。 相似文献
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啤酒苦味主要来源于酒花。在啤酒生产过程中由于酒花质量差,添加方法不当,麦汁及啤酒风味物质组成不合理,酵母自溶等原因,都可能使啤酒苦味发生变化。如何保持啤酒酒体协调,风味稳定,尽可能减少啤酒不正常苦味,则是本文所要探讨的问题。l多酚物质对啤酒苦味的影响酿造啤酒所用的大麦、酒花中都含有多酚物质多元酚及其衍生物。造成啤酒苦味的多酚物质主要存在于大麦皮壳及糊份层中。多酚物质在大麦中约为0.1~0.3%,酒花中含量为4~14%,其中60%为花色音。多酚物质对啤酒风味起着重要作用。多酚物质在多酚氧化酶和过氧化氢酶的作… 相似文献
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啤酒生产过程中氧化还原酶系的研究 总被引:10,自引:0,他引:10
啤酒生产过程中的氧化还原酶与啤酒风味陈化紧密相关。低水分下,其耐温活性远高于其它几种酶,在麦芽中酶活升高比例最大(与大麦中的酶活相比),其在糖化过程中氧化多酚的能力远大于多酚氧化酶。糖化过程中迅速失活,而脂肪酸氧化酶在糖化起始的低温阶段仍有部分酶活,影响不饱和脂肪酸的氧化。焙燥过程中适当延长50~70℃温度段时间,可有效降低麦芽中氧化还原酶的酶活。结合这些酶的性质,从部分抑制它们的活性角度出发,在糖化过程中,于50~60℃进行隔氧处理,可经济、有效的减少影响风味氧化的前驱物质的含量。同一质量等级不同品种的麦芽的氧化还原酶系差别相当大,相应制得的麦汁中与风味氧化有关的物质含量也有较大差别,这可能是造成不同批次原料酿造的成品啤酒风味保鲜期不稳定的原因之一。 相似文献
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论多酚物质对啤酒质量的影响及控制 总被引:1,自引:1,他引:1
论多酚物质对啤酒质量的影响及控制衣艳萍范亚君(黑龙江省双鸭山市啤酒厂)刘庆杰(黑龙江省鹤岗啤酒厂)一、多酚物质的来源1.大麦大麦中含有较多的酚类物质,在大麦干物质中约占0.1%-0.3%,主要存在于谷皮和糊粉层,少量存在于胚乳。蛋白质含量低的大麦其多... 相似文献
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Simon P. Clarkson Peter J. Large Charles W. Bamforth 《Journal of the Institute of Brewing》1992,98(2):111-115
Off the enzymes that may be involved in the scavenging off oxygen radicals in barley and malt, superoxide dismutase, catalase and peroxidase all increase their specific activities during malting, whereas polyphenol oxidase decreases to zero. Of these, however, only the isoenzymes of peroxidase survive (in part) in the mash, and are responsible for the oxidation of polyphenolic materials. The concentration of hydrogen peroxide normally found in wort limits their action. Addition of hydrogen peroxide to the mash or its generation via a glucose oxidase system greatly increases haze formation, decreases the polyphenol content and causes the development of a red coloration. When the same amount of the different malt peroxidase isoenzymes was added to mashes, the intensity of the red colour varied according to the isoenzyme used. The worts produced by enhanced peroxidation afford more colloidally stable beers. The effects however are limited by the dissolved oxygen concentration in the wort. 相似文献
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以邻苯二酚为底物通过分光光度计法,对国产大麦中多酚氧化酶(PPO)的酶学特性进行了研究。同时建立了 PPO 活性测定方法,确定了大麦 PPO 的米氏常数 Km 为1.96mol/L。结果表明,最适测定条件为酶添加量≤6mL、反应时间为4min,检测波长为415nm;国产大麦 PPO 的最适作用温度为80℃,最适作用 pH 为7.6。PPO 在沸水中处理6min 即可有效抑制其活性。实验中同时考察了柠檬酸、抗坏血酸对大麦 PPO 的抑制作用。 相似文献
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Enzyme inactivation is vital in fruit and vegetable juice processing, and selective inactivation is a major focus of enzyme inactivation. We used electrospray treatment to investigate directional enzyme inactivation in cabbage juice. Peroxidase and polyphenol oxidase in cabbage juice are the enzymes causing deterioration, whereas myrosinase is a beneficial enzyme. The particle size distribution, zeta potential and secondary and tertiary structures of the enzyme proteins were evaluated before and after enzyme inactivation. After the electrospray treatment, the relative activities of peroxidase, polyphenol oxidase and myrosinase in the mixed-enzyme simulation system were 4.09%, 5.62% and 84.67%, respectively, and those in the cabbage juice were 6.68%, 5.24% and 77.34%, respectively. Additionally, electrospray treatment induced substantial aggregation of peroxidase and polyphenol oxidase in the mixed-enzyme solution, and the secondary and tertiary structures of peroxidase and polyphenol oxidase were destroyed. Moreover, the conformation of myrosinase was preserved. These findings indicated that electrospray treatment can cause selective inactivation of peroxidase and polyphenol oxidase while preserving myrosinase activity. 相似文献
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Andreas Finger 《Journal of the science of food and agriculture》1994,66(3):293-305
Flavanols (catechins and gallocatechins) isolated from green tea leaves (Camellia sinensis) (L) O Kuntze) were treated in vitro with polyphenol oxidase, peroxidase and a combination of both. The flavanol levels and those of the products formed were monitored by reversed-phase high-performance liquid chromatography (HPLC using spectrophotometric detection at 280 and 380 nm. Flavanols and theaflavins were quantified, whilst integrated peak areas are given for the remaining compounds. After fermentation in the presence of polyphenol oxidase higher levels of theaflavins and resolved thearubigins were obtained, whilst peroxidase produced higher amounts of chromatographically unresolved thearubigins of higher molecular weight, observed as a rise in the HPLC baseline, in the presence of peroxidase a significant decrease in the levels of all flavonol glycosides was observed, whilst in the presence of polyphenol oxidase only myricetin glycoside levels decreased. 相似文献
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Pressure Induced Inactivation of Selected Food Enzymes 总被引:11,自引:0,他引:11
ISABEL SEYDERHELM STEFAN BOGUSLAWSKI GÜNTHER MICHAELIS DIETRICH KNORR 《Journal of food science》1996,61(2):308-310
Pectinesterase, lipase, polyphenol oxidase, lipoxygenase, peroxidase, lactoperoxidase, phosphatase and catalase have been examined at distinct conditions within a pressure range of 0.1 to 900 MPa, temperatures from 25°C to 60°C, pH 3 to 7, and time of treatment of 2 min to 45 min. Results in model buffers made it possible to rank the enzymes according to their pressure induced inactivation in the following order: lipoxygenase, lactoperoxidase, pectinesterase, lipase, phosphatase, catalase, polyphenol oxidase, peroxidase. A combination of pressure with moderate temperature increased the degree of enzyme inactivation. Pressure treatment of real food systems showed a protective effect of food ingredients on the pressure inactivation of most enzymes evaluated. For example sucrose protected pectinesterase from inactivation by pressure while lactoperoxidase and lipoxigenase were as stable in milk as in buffer. 相似文献
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本研究以中华猕猴桃为实验材料,采用四种浓度0、250、500、1000 μL/L乙醇熏蒸处理,置于0℃贮藏,分别在第0、14、28、42、56、70 d测定其果实硬度、维生素C含量、叶绿素含量、过氧化氢酶(CAT)、多酚氧化酶(PPO)、过氧化物酶(POD)、总酚及类黄酮含量。结果表明:经过乙醇熏蒸处理,呼吸强度明显受到抑制,保持了果实的硬度、减缓了维生素C含量、叶绿素含量的下降速率及褐变发生情况,提高了CAT的活性,保护PPO活性,但对POD影响不显著,同时也提高了总酚、类黄酮等抗氧化物质的含量,达到了保鲜效果,有效延长了中华猕猴桃的货架期。500 μL/L乙醇熏蒸处理能够较好地保护果实的品质,降低酶活性,提高抗氧化物质含量,减缓果实衰老。 相似文献